Use of spray dried animal plasma as an alternative to antimicrobial medication in weanling pigs

Two experiments were conducted in order to evaluate spray dried animal plasma (SDAP) as an alternative to antimicrobial prophylactic medication with colistin in weaned pigs. Experiment 1 was conducted with 96 piglets (21-day-old) and Experiment 2 was conducted with 128 piglets, (64 weaned at 22 days of age and 64 at 32 days of age). In both experiments the effects of the use of SDAP and/or colistin were compared. Four dietary treatments were used in a factorial arrangement: negative control (N), diet containing SDAP (P), diet containing colistin (C) and diet containing both SDAP and colistin (PC). SDAP was added to diets P and PC at 50 g kg−1 between days 0–14 of the trial and at 20 g kg−1 from day 15 to the end of the trial. In Experiment 1, SDAP improved average daily gain (ADG; +42 g per day; P<0.05) and feed conversion ratio (FCR; −0.13; P<0.01) between days 0–14, and FCR (−0.03; P<0.05) between days 0–35 compared to the diets without SDAP. Colistin improved FCR between days 0–14 and 0–35 (−0.13; P<0.05 and −0.05; P<0.01, respectively) compared to the diets without colistin. No significant effects (P>0.05) were observed between days 15–35. No interaction between SDAP and colistin was found, suggesting that their modes of action are independent. In Experiment 2, SDAP improved FCR between days 0–14 and 0–28 (−0.05; P=0.08 and −0.05; P<0.05, respectively) with respect to the diets without SDAP. No significant effect (P>0.05) of colistin for any of the parameters studied was detected in any of the experimental periods. FCR, however, was only improved in the older pigs between days 0–28 post-weaning (−0.03; P<0.05). No significant interactions between SDAP, colistin and age at weaning were observed with any parameter (P>0.05). It is concluded that SDAP may be a good alternative to medication with colistin as both products gave similar improvements in performance. The positive effects of SDAP and colistin were more important during the first 2 weeks post-weaning and appeared to be higher in pigs weaned at a younger age, although no significant interaction between age at weaning and SDAP or colistin was observed.